I started a video series on my YouTube channel a few months ago that
serves the purpose of visualizing piano rolls in the piano learning
program Synthesia. The audio is good quality, too.

I can't take requests, unfortunately, as I don't have constant
Internet access (if I got a MIDI file in my email then I would forget
to film it).

Note to scanners whose MIDI files were used: I don't credit the scan
sources as I upload the video in bulk batches and they take a while
just to edit the titles. Most scan sites are easily found.

Here's the link to the playlist where I have collected all the videos:
https://tinyurl.com/y2gcnqbu 

Piotr Barcz